An intermitent and seemingly random "stutter" effect occurs, but it is not related to any hardward slowdown or overload. After attempting many fixes (including reinstalling/downgrading nvidia drivers, installing the flatpak version of steam, changing proton versions, and tweaking nvidia driver settings), it seems to be an issue related to the X11 display server. If you are using multiple monitors with different framerates, this hard to describe framedrop-esque effect occurs. The framerate/responsetime/GPU activity doesn't actually change, but visually, the slowdown occurs. If I unplug all but the main monitor, the issue disappears.